CREATE TABLE IF NOT EXISTS contact_groups (
    id TEXT PRIMARY KEY,
    name TEXT NOT NULL UNIQUE,
    created_at TEXT NOT NULL DEFAULT (datetime('now')),
    updated_at TEXT NOT NULL DEFAULT (datetime('now'))
);

CREATE TABLE IF NOT EXISTS contact_group_members (
    group_id TEXT NOT NULL,
    contact_id TEXT NOT NULL,
    PRIMARY KEY (group_id, contact_id),
    FOREIGN KEY (group_id) REFERENCES contact_groups(id) ON DELETE CASCADE,
    FOREIGN KEY (contact_id) REFERENCES contacts(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_cgm_contact_id ON contact_group_members(contact_id);